The present invention relates to a floppy disk driving apparatus, particularly to a circuit which generates a disk change signal for detecting existence of a floppy disk inserted thereto.
Conventionally known is a floppy disk driving apparatus with an index sensor which detects the rotation of the floppy disk and a disk-in sensor which detects the insertion of the floppy disk. FIG. 1A and 1B show schematic diagram of the conventional floppy disk driving apparatus.
Referring to FIG. 1A, when a floppy disk is inserted into a floppy disk driving apparatus, light-receiving transistor PQ1 is turned off, cutting off an emitted light from the light emitting diode PD.sub.1 of the disk-in sensor S1. If light-receiving transistor PQ1 is turned off, a logic signal of a line 1 becomes high level signal and then the high level signal is applied to clear terminal a flip-flop FF.sub.1.
Applying disk change reset signal from a controller in the clock terminal CLK of the flip-flop FF.sub.1, thereby outputs the logic high level signal through the output terminal Q of the flip-flop FF.sub.1 and then the disk-in sensor detects the insertion of the floppy disk. Changing the disk change signal logic "high level" outputted from the flip-flop, the controller senses the disk change signal, and thereby regularly controls the floppy disk driving apparatus.
When the floppy disk is ejected from the floppy disk driving apparatus, the disk-in sensor S1 is operated, and outputted logic "low level signal" through the line 1, thereby the output signal of logic "low level signal" is applied to the clear terminal CLR of the flip-flop FF.sub.1 and then the flip-flop is cleared. Thereby, the logic "low level signal" is outputted through the output terminal Q of the flip-flop FF.sub.1. When the disk change signal outputted from the output terminal of the flip-flop FF.sub.1 becomes the logic "low level signal", the controller detects a extraction of the floppy disk.
Referring to FIG. 1B which is a circuit for detecting a rotation of the floppy disk, an index sensor S2 is operated by a cycle the rotation of the floppy disk, thereby an index sensing circuit 10 detects an index pulse. Conventional floppy disk driving apparatus as shown FIG. 1A and 1B comprises the disk-in sensor and the index sensor, thereby a circuit, of floppy disk driving apparatus is complex and requires a large printed circuit board.